drivers/cpufreq/powernow-k6.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
   4  *  (C) 2000-2003  Dave Jones, Arjan van de Ven, Janne Pänkälä,
   5  *                 Dominik Brodowski.
   6  *
   7  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/cpufreq.h>
  16 #include <linux/ioport.h>
  17 #include <linux/timex.h>
  18 #include <linux/io.h>
  19
  20 #include <asm/cpu_device_id.h>
  21 #include <asm/msr.h>
  22
  23 #define POWERNOW_IOPORT 0xfff0          /* it doesn't matter where, as long
  24                                            as it is unused */
  25
  26 static unsigned int                     busfreq;   /* FSB, in 10 kHz */
  27 static unsigned int                     max_multiplier;
  28
  29 static unsigned int                     param_busfreq = 0;
  30 static unsigned int                     param_max_multiplier = 0;
  31
  32 module_param_named(max_multiplier, param_max_multiplier, uint, S_IRUGO);
  33 MODULE_PARM_DESC(max_multiplier, "Maximum multiplier (allowed values: 20 30 35 40 45 50 55 60)");
  34
  35 module_param_named(bus_frequency, param_busfreq, uint, S_IRUGO);
  36 MODULE_PARM_DESC(bus_frequency, "Bus frequency in kHz");
  37
  38 /* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
  39 static struct cpufreq_frequency_table clock_ratio[] = {
  40         {0, 60,  /* 110 -> 6.0x */ 0},
  41         {0, 55,  /* 011 -> 5.5x */ 0},
  42         {0, 50,  /* 001 -> 5.0x */ 0},
  43         {0, 45,  /* 000 -> 4.5x */ 0},
  44         {0, 40,  /* 010 -> 4.0x */ 0},
  45         {0, 35,  /* 111 -> 3.5x */ 0},
  46         {0, 30,  /* 101 -> 3.0x */ 0},
  47         {0, 20,  /* 100 -> 2.0x */ 0},
  48         {0, 0, CPUFREQ_TABLE_END}
  49 };
  50
  51 static const u8 index_to_register[8] = { 6, 3, 1, 0, 2, 7, 5, 4 };
  52 static const u8 register_to_index[8] = { 3, 2, 4, 1, 7, 6, 0, 5 };
  53
  54 static const struct {
  55         unsigned freq;
  56         unsigned mult;
  57 } usual_frequency_table[] = {
  58         { 350000, 35 }, // 100   * 3.5
  59         { 400000, 40 }, // 100   * 4
  60         { 450000, 45 }, // 100   * 4.5
  61         { 475000, 50 }, //  95   * 5
  62         { 500000, 50 }, // 100   * 5
  63         { 506250, 45 }, // 112.5 * 4.5
  64         { 533500, 55 }, //  97   * 5.5
  65         { 550000, 55 }, // 100   * 5.5
  66         { 562500, 50 }, // 112.5 * 5
  67         { 570000, 60 }, //  95   * 6
  68         { 600000, 60 }, // 100   * 6
  69         { 618750, 55 }, // 112.5 * 5.5
  70         { 660000, 55 }, // 120   * 5.5
  71         { 675000, 60 }, // 112.5 * 6
  72         { 720000, 60 }, // 120   * 6
  73 };
  74
  75 #define FREQ_RANGE              3000
  76
  77 /**
  78  * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
  79  *
  80  * Returns the current setting of the frequency multiplier. Core clock
  81  * speed is frequency of the Front-Side Bus multiplied with this value.
  82  */
  83 static int powernow_k6_get_cpu_multiplier(void)
  84 {
  85         unsigned long invalue = 0;
  86         u32 msrval;
  87
  88         local_irq_disable();
  89
  90         msrval = POWERNOW_IOPORT + 0x1;
  91         wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
  92         invalue = inl(POWERNOW_IOPORT + 0x8);
  93         msrval = POWERNOW_IOPORT + 0x0;
  94         wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
  95
  96         local_irq_enable();
  97
  98         return clock_ratio[register_to_index[(invalue >> 5)&7]].driver_data;
  99 }
 100
 101 static void powernow_k6_set_cpu_multiplier(unsigned int best_i)
 102 {
 103         unsigned long outvalue, invalue;
 104         unsigned long msrval;
 105         unsigned long cr0;
 106
 107         /* we now need to transform best_i to the BVC format, see AMD#23446 */
 108
 109         /*
 110          * The processor doesn't respond to inquiry cycles while changing the
 111          * frequency, so we must disable cache.
 112          */
 113         local_irq_disable();
 114         cr0 = read_cr0();
 115         write_cr0(cr0 | X86_CR0_CD);
 116         wbinvd();
 117
 118         outvalue = (1<<12) | (1<<10) | (1<<9) | (index_to_register[best_i]<<5);
 119
 120         msrval = POWERNOW_IOPORT + 0x1;
 121         wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
 122         invalue = inl(POWERNOW_IOPORT + 0x8);
 123         invalue = invalue & 0x1f;
 124         outvalue = outvalue | invalue;
 125         outl(outvalue, (POWERNOW_IOPORT + 0x8));
 126         msrval = POWERNOW_IOPORT + 0x0;
 127         wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
 128
 129         write_cr0(cr0);
 130         local_irq_enable();
 131 }
 132
 133 /**
 134  * powernow_k6_target - set the PowerNow! multiplier
 135  * @best_i: clock_ratio[best_i] is the target multiplier
 136  *
 137  *   Tries to change the PowerNow! multiplier
 138  */
 139 static int powernow_k6_target(struct cpufreq_policy *policy,
 140                 unsigned int best_i)
 141 {
 142
 143         if (clock_ratio[best_i].driver_data > max_multiplier) {
 144                 pr_err("invalid target frequency\n");
 145                 return -EINVAL;
 146         }
 147
 148         powernow_k6_set_cpu_multiplier(best_i);
 149
 150         return 0;
 151 }
 152
 153 static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
 154 {
 155         struct cpufreq_frequency_table *pos;
 156         unsigned int i, f;
 157         unsigned khz;
 158
 159         if (policy->cpu != 0)
 160                 return -ENODEV;
 161
 162         max_multiplier = 0;
 163         khz = cpu_khz;
 164         for (i = 0; i < ARRAY_SIZE(usual_frequency_table); i++) {
 165                 if (khz >= usual_frequency_table[i].freq - FREQ_RANGE &&
 166                     khz <= usual_frequency_table[i].freq + FREQ_RANGE) {
 167                         khz = usual_frequency_table[i].freq;
 168                         max_multiplier = usual_frequency_table[i].mult;
 169                         break;
 170                 }
 171         }
 172         if (param_max_multiplier) {
 173                 cpufreq_for_each_entry(pos, clock_ratio)
 174                         if (pos->driver_data == param_max_multiplier) {
 175                                 max_multiplier = param_max_multiplier;
 176                                 goto have_max_multiplier;
 177                         }
 178                 pr_err("invalid max_multiplier parameter, valid parameters 20, 30, 35, 40, 45, 50, 55, 60\n");
 179                 return -EINVAL;
 180         }
 181
 182         if (!max_multiplier) {
 183                 pr_warn("unknown frequency %u, cannot determine current multiplier\n",
 184                         khz);
 185                 pr_warn("use module parameters max_multiplier and bus_frequency\n");
 186                 return -EOPNOTSUPP;
 187         }
 188
 189 have_max_multiplier:
 190         param_max_multiplier = max_multiplier;
 191
 192         if (param_busfreq) {
 193                 if (param_busfreq >= 50000 && param_busfreq <= 150000) {
 194                         busfreq = param_busfreq / 10;
 195                         goto have_busfreq;
 196                 }
 197                 pr_err("invalid bus_frequency parameter, allowed range 50000 - 150000 kHz\n");
 198                 return -EINVAL;
 199         }
 200
 201         busfreq = khz / max_multiplier;
 202 have_busfreq:
 203         param_busfreq = busfreq * 10;
 204
 205         /* table init */
 206         cpufreq_for_each_entry(pos, clock_ratio) {
 207                 f = pos->driver_data;
 208                 if (f > max_multiplier)
 209                         pos->frequency = CPUFREQ_ENTRY_INVALID;
 210                 else
 211                         pos->frequency = busfreq * f;
 212         }
 213
 214         /* cpuinfo and default policy values */
 215         policy->cpuinfo.transition_latency = 500000;
 216         policy->freq_table = clock_ratio;
 217
 218         return 0;
 219 }
 220
 221
 222 static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
 223 {
 224         unsigned int i;
 225
 226         for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
 227                 if (clock_ratio[i].driver_data == max_multiplier) {
 228                         struct cpufreq_freqs freqs;
 229
 230                         freqs.old = policy->cur;
 231                         freqs.new = clock_ratio[i].frequency;
 232                         freqs.flags = 0;
 233
 234                         cpufreq_freq_transition_begin(policy, &freqs);
 235                         powernow_k6_target(policy, i);
 236                         cpufreq_freq_transition_end(policy, &freqs, 0);
 237                         break;
 238                 }
 239         }
 240         return 0;
 241 }
 242
 243 static unsigned int powernow_k6_get(unsigned int cpu)
 244 {
 245         unsigned int ret;
 246         ret = (busfreq * powernow_k6_get_cpu_multiplier());
 247         return ret;
 248 }
 249
 250 static struct cpufreq_driver powernow_k6_driver = {
 251         .verify         = cpufreq_generic_frequency_table_verify,
 252         .target_index   = powernow_k6_target,
 253         .init           = powernow_k6_cpu_init,
 254         .exit           = powernow_k6_cpu_exit,
 255         .get            = powernow_k6_get,
 256         .name           = "powernow-k6",
 257         .attr           = cpufreq_generic_attr,
 258 };
 259
 260 static const struct x86_cpu_id powernow_k6_ids[] = {
 261         { X86_VENDOR_AMD, 5, 12 },
 262         { X86_VENDOR_AMD, 5, 13 },
 263         {}
 264 };
 265 MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);
 266
 267 /**
 268  * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
 269  *
 270  *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
 271  * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
 272  * on success.
 273  */
 274 static int __init powernow_k6_init(void)
 275 {
 276         if (!x86_match_cpu(powernow_k6_ids))
 277                 return -ENODEV;
 278
 279         if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
 280                 pr_info("PowerNow IOPORT region already used\n");
 281                 return -EIO;
 282         }
 283
 284         if (cpufreq_register_driver(&powernow_k6_driver)) {
 285                 release_region(POWERNOW_IOPORT, 16);
 286                 return -EINVAL;
 287         }
 288
 289         return 0;
 290 }
 291
 292
 293 /**
 294  * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
 295  *
 296  *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
 297  */
 298 static void __exit powernow_k6_exit(void)
 299 {
 300         cpufreq_unregister_driver(&powernow_k6_driver);
 301         release_region(POWERNOW_IOPORT, 16);
 302 }
 303
 304
 305 MODULE_AUTHOR("Arjan van de Ven, Dave Jones, "
 306                 "Dominik Brodowski <linux@brodo.de>");
 307 MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
 308 MODULE_LICENSE("GPL");
 309
 310 module_init(powernow_k6_init);
 311 module_exit(powernow_k6_exit);